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All Textbook Solutions for Chemistry for Engineering Students

For each of the following, suggest appropriate rate units Driving from one place to another Drying dishes by hand The heating wings of a mosquito Eyes blinking 11.11PAE Rank the following in order of increasing reaction rate. (a) Dynamite exploding (b) Iron rusting (c) Paper burning 11.13PAE Candle wax is a mixture of hydrocarbons. In the reaction of oxygen with candle w ax in Figure 11.2, the rate of consumption of oxygen decreased with time after the flask was covered, and eventually' the flame went out. From the perspective of the kinetic-molecular theory, describe what is happening in the flask. FIGURE 11.2 When a candle burns in a closed container, the flame will diminish and eventually go out. As the amount of oxygen present decreases, the rate of combustion will also decrease. Eventually, the rate of combustion is no longer sufficient to sustain the flame even though there is still some oxygen present in the vessel.11.15PAE The reaction for the Haber process, the industrial production of ammonia, is N2(g)+3H2(g)2NH3(g) Assume that under certain laboratory conditions ammonia is produced at the rate of 6.29 ×10-5 molL-1s-1. At what rate is nitrogen consumed? At what rate is hydrogen consumed?11.17 Ammonia can react with oxygen to produce nitric oxide and water: 4NH3(g)+5O2(g)4NO(g)+6H2O(g) If the rate at which ammonia is consumed in a laboratory experiment is 4.23 ×10-4 mol L_1s_l, at what rate is oxygen consumed? At what rate is NO produced? At what rate is water vapor produced?The following data were obtained in the decomposition of H2O2(aq) to O2(g) and H2OThe rate at which oxygen gas was produced was measured. (No oxygen was present initially.) Time (min) Volume of O2(mL) 3.3 10.4 6.9 17.3 Calculate the average rate in mL/min for the first 3.3 minutes. Calculate the average rate in mL/min for the first 6.9 minutes.11.19PAE Experimental data are listed here for the reaction B: Time (s) IB] (mol/L) 0.00 0.000 10.0 0.326 20.0 0.572 30.0 0.750 40.0 0.890 Prepare a graph from these data, connect the points with a smooth line, and calculate the rate of change of [B] for each 10-s interval from 0.0 to 40.0 s. Does the rate of change decrease from one time interval to the next? Suggest a reason for this result. How is the rate of change of [AJ related to the rate of change of [B] in each time interval? Calculate the rate of change of [AJ for the time interval from 10.0 to 20.0 s. What is the instantaneous rate, A[B]/Ar, when [BI = 0.750 mol/L?Azomethane, CH3NNCH3, is not a stable compound, and once generated, it decomposes. The rate of decomposition was measured by monitoring the partial pressure of azomethane, in torr: Time (min)015304875 Pressure (torr)36.230.024.919.313.1 Plot the data and determine the instantaneous rate of decomposition of azomethane at t = 20 min.11.22PAE A reaction has the experimental rate equation Rate = k[A]2. How will the rate change if the concentration of A is halved?Second-order rate constants used in modeling atmospheric chemistry are commonly reported in units of cm3 molecule-1s-1. Convert the following rate constants to L mol-1s-1: 3.51014 cm3 molecule-1 s-1 7.11018 cm3 molecule-1 s-1 6.11030 cm3 molecule-1s-1 For each of the rate laws below, what is the order of the reaction with respect to the hypothetical substances X, Y, and Z? What is the overall order? (a) Rate = k [X][Y][Zl, (b) Rate = k [X]-[Y]1/2[Z], (c) Rate = k [X]L5[Y]-1, (d) Rate = k [X]/[Y]2 11.26 The reaction of C(Xg) with NO2(g) is second order in NO2and zero order in CO at temperatures less than 500 K. Write the rate law for the reaction. How will the reaction rate change if the NO2concentration is halved? How will the reaction rate change if the concentration of CO is doubled?11.27PAE 11.28PAE The hypothetical reaction, A + B —*C, has the rate law Rate = When [A] is doubled and [B] is held constant, the rate doubles. But the rate increases fourfold when [B] is doubled and [A] is held constant. What are the values of'x and y?The rate of the decomposition of hydrogen peroxide, H2O2, depends on the concentration of iodide ion present. The rate of decomposition was measured at constant temperature and pressure for various concentrations of H2O2and of KI. The data appear below. Determine the order of reaction for each substance, write the rate law, and evaluate the rate constant. Rate [H2OJ [Kll (mL min-’) (mol L ’) (mol L ’) 0.090 0.15 0.033 0.178 0.30 0.033 0.184 0.15 0.066 11.31PAE 11.32 The following experimental data were obtained for the reaction 2A + 3 B—C + 2D [A](mol L 1) [B](mol L ’) Rate = A(C]/Af (mol L-1 s-1) 0.127 0.15 0.033 0.127 0.30 0.132 0.255 0.15 0.066 Determine the reaction order for each reactant and the value of the rate constant.The following experimental data were obtained for the reaction of \'I14* and NOf in acidic solution. NH/(aq) + NO2-(aq) — N;(g) + 2 H,O(f) INH/I (mol L1) [NO21 (mol L-1, Rate = A[NJ/At (mol L-1 s’) 0.0092 0.098 3.33 X IO"7 0.0092 0.049 1.66 X 10‘7 0.0488 0.196 3.51 X 10"6 0.0249 0.196 1.80 X 10-6 Determine the rate law for this reaction and calculate the rate constant.11.34 Rate data were obtained at 25°C for the following reaction. What is the rate law expression for this reaction? A + 2B — C + 2D Expt Initial [A] (mol L-’) Initial [B] (mol L_1) Initial Rate ofFormation of C (mol L-1 min-1) 1 0.10 0.10 3.0 X 10~4 2 0.30 0.30 9.0 X 10"4 3 0.10 0.30 3.0 X 10~4 4 0.20 0.40 6.0 X 10"4 11.35 For the reaction 2 NO(g) + 2 H?(g) — N,(g) + 2 H,O(g) at 1100°C, the following data have been obtained: [NOJ [HJ Rate = A(N2]/At (mol L~1) (mol L_1) (mol L-1 s_1) 5.0 X 10’1 0.32 0.012 1.0 X 10~’ 0.32 0.048 1.0 X 10"2 0.64 0.096 Derive a rate law for the reaction and determine the value of the rate constant.The reaction NO(g) + O,(g) — NO,(g) + 0(g) plays a role in the formation of nitrogen dioxide in automobile engines. Suppose that a series of experiments measured the rate of this reaction at 500 K and produced the following data; [NO] (mol L ’) [OJ (mol L 1) Rate = -A[NO]/Af (mol L_1 s-1) 0.002 0.005 8.0 X 10"'7 0.002 0.010 1.6 X 10-'6 0.006 0.005 2.4 X IO-'6 Derive a rate law for the reaction and determine the value of the rate constant.11.37PAE 11.38PAE The decomposition of N2O5 in solution in carbon tetrachloride is a first-order reaction: 2N2O5 — 4NO2 + O2 The rate constant at a given temperature is found to be 5.25 X IO-4 s_I. If the initial concentration of N,OS is 0.200 M, what is its concentration after exactly 10 minutes have passed?In Exercise 11.39, if the initial concentration of N2Oj is 0.100 .\1. how long will it take for the concentration to drop to 0.0100 times its original value? The decomposition of N2O5 in solution in carbon tetrachloride is a first-order reaction: 2N2O5—»4NO2 + O2 The rate constant at a given temperature is found to be 5.25 X 10-4 s-’. If the initial concentration of N2O5 is 0.200 M, what is its concentration after exactly 10 minutes have passed?11.41 For a drug to be effective in treating an illness, its levels in the bloodstream must be maintained for a period of time. One way to measure the level of a drug in the body is to measure its rate of appearance in the urine. The rate of excretion of penicillin is first order, with a half-life of about 30 min. If a person receives an injection of 25 mg of penicillin at t = 0, how much penicillin remains in the body after 3 hours?Amoxicillin is an antibiotic packaged as a powder. When it is used to treat babies and small animals, the pharmacist or veterinarian must suspend it in water, so that it can be administered orally with a medicine dropper. The label says to dispose of unused suspension after 14 days. It also points out that refrigeration is required. In the context of this chapter, what is implied in the latter two statements?As with any drug, aspirin (acetylsalicylic acid) must remain in the bloodstream long enough to be effective. Assume that the removal of aspirin from the bloodstream into the urine is a lirst-order reaction, with a half-life of about 3 hours. The instructions on an aspirin bottle say to take 1 or 2 tablets every 4 hours. If a person takes 2 aspirin tablets, how much aspirin remains in the bloodstream when it is time for the second dose? (A standard tablet contains 325 mg of aspirin.)11.44 A possible reaction for the degradation of the pesticide DDT to a less harmful compound was simulated in the laboratory. The reaction was found to be first order, with k = 4.0 X 10_H s"' at 25°C. What is the half-life for the degradation of DDT in this experiment, in years?The initial concentration of the reactant in a tirst-order reaction A —» products is 0.64 rnol/L and the half-life is 30.0 s. Calculate the concentration of the reactant exactly 60 s after initiation of the reaction. How long would it take for the concentration of the reactant to drop to one-eighth its initial value? How long would it take for the concentration of the reactant to drop to 0.040 mol/L?A substance undergoes first-order decomposition. After 40.0 min at 500°C, only 12.5% of the original sample remains. YYliat is the half-life of the decomposition? If the original sample weighed 243 g, how much would remain after 2.00 h?11.47PAE 11.48 The following data were collected for the decomposition of NT),-: Time, f (min) [N2Os] (mol L-1) 0 0.200 5 0.171 10 0.146 15 0.125 20 0.106 25 0.0909 30 0.0777 35 0.0664 40 0.0570 Use appropriate graphs to determine the rate constant for this reaction. Find the half-life of the reaction.The rate of photodecomposition of the herbicide piclo- ram in aqueous systems was determined by exposure to sunlight for a number of days. One such experiment produced the following results. (Data from R.T. Hedlun and C.R. Youngson, “The Rates of Photodecomposition of Picloram in Aqueous Systems," Fate of Organic Pesticides in tbe Aquatic Environment, Advances in Chemistry Series, #111, American Chemical Society (1972), 159—172.) Exposure Time, t (days) [Pidoram] (mol L_1) 0 4.14 X 10-6 7 3.70 X 10-6 14 3.31 X 10-6 21 2.94 X 10~6 28 2.61 X 10~6 35 2.30 X 10-6 42 2.05 X 10-6 49 1.82 X 10"6 56 1.65 X 10-6 Determine the order of reaction, the rate constant, and the half-life for the photodecomposition of picloram.11.50PAE 11.51 Peroxyacetyl nitrate (PAN) has the chemical formula CtHjNOj and is an important lung irritant in photochemical smog. An experiment to determine the decomposition kinetics of PAN gave the data below. Determine the order of reaction and calculate the rate constant for the decomposition of PAN. Time, t (min) Partial Pressure of PAN (torr) 0.0 2.00 X 10~’ 10.0 1.61 X 10~} 20.0 1.30 X 10_J 30.0 1.04 X 10"’ 40.0 8.41 X 10-4 50.0 6.77 x 10-4 60.0 5.45 X 10-4 Hydrogen peroxide (H20i) decomposes into water and oxygen: H,O2(aq) — H,O(f) + ^O2(g) Ordinarily this reaction proceeds rather slowly, hut in the presence of some iodide ions (I-), the decomposition is much faster. Ihe decomposition in the presence of iodide was studied at 20°C, and the data were plotted in various ways. Use the graphs below to answer the questions that follow. What is the order of reaction for the decomposition of hydrogen peroxide? Find the numerical value of the rate constant at 20°C, including the correct units. Obtain an estimate of the initial rate of reaction in the experiment that produced the graphs (i.e., the rate at t = 0 in the graphs).11.53 The reaction in which CO, decomposes to CO and a free radical oxygen atom, O, has an activation energy of 460 kJ mol_l. The frequency’ factor is 2 X 1011s-1. What is the rate constant for this reaction 3t 298 K?use the kineticmolecular theory to explain why an increase in temperature increases reaction rate.The following rate constants were obtained in an experiment in which the decomposition of gaseous N2O; was studied as a function of temperature. The products were NO, and NO,. Temperature (K) 3.5 x 10_i 298 2.2 x 10"4 308 6.8 X IO-4 318 3.1 x 10 1 328 Determine Etfor this reaction in kj/mol.The table below presents measured rate constants for the reaction of NO with ozone at three temperatures. From these data, determine the activation energy’ of the reaction in kj/mol. (Assume the temperatures all have at least two significant figures.) k (L mol-1 s’1) Temperature (K) 1.3 X 106 200 4.4 X 106 250 9.9 X 106 300 11.57PAE 11.58PAE Can a reaction mechanism ever be proven correct? Can it be proven incorrect?11.60PAE Describe how the Chapman cycle is a reaction mechanism. What is the molecularity of each reaction in the Chapman cycle?11.62PAE The following mechanism is proposed for a reaction: NO + Br2 —* NOBr2 (slow) NOBr2 + NO —»2 NOBr (fast) Write the overall equation for the reaction. What is the rate-determining step? WTiat is the intermediate in this reaction? What is the molecularity of each step of the reaction? Write the rate expression for each step.11.64 HBr is oxidized in the following reaction: 4 HBr(g) + O2(g) —• 2 H2O(g) + 2 Br,(g) A proposed mechanism is HBr + O2 -* HOOBr (slow) HOOBr + HBr — 2 HOBr (fast) HOBr + HBr — H2O + Bn (fast) Show that this mechanism can account for the correct stoichiometry. Identify all intermediates in this mechanism. What is the molecularity of each elementary’ step? Write the rate expression for each elementary' step. Identify the rate-determining step.11.65PAE 11.66PAE What distinguishes homogeneous and heterogeneous catalysis?11.68PAE In Chapter 3, we discussed the conversion of biomass into biofuels. One important area of research associated with biofuels is the identification and development of suitable catalysts to increase the rate at which fuels can be produced. Do a web search to find an article describing biofuel catalysts. Then, write one or two sentences describing the reactions being catalyzed, and identify the catalyst as homogeneous or heterogeneous.The label on a bottle of 3% (by volume) hydrogen peroxide, H2O2, purchased at a grocery store, states that the solution should be stored in a cool, dark place. H2O2decomposes slowly over time, and the rate of decomposition increases with an increase in temperature and in the presence of light. However, the rate of decomposition increases dramatically if a small amount of powdered MnO- is added to the solution. The decomposition products are H2O and O2. MnO2 is not consumed in the reaction. Write the equation for the decomposition of H2O2. What role does MnO2 play? In the chemistry lab, a student substituted a chunk of MnO2 for the powdered compound. The reaction rate was not appreciably increased. WTiat is one possible explanation for this observation? Is MnO2 part of the stoichiometry of the decomposition of H2O2?11.71PAE 11.72PAE 11.73PAE 11.74 The AQI includes six levels, including several that describe air that is not healthy to breathe. YYTiat are the possible advantages and disadvantages of proposing to collapse the AQI to only four levels?11.75PAE 11.76PAE 11.77PAE 11.78PAE 11.79PAE 11.80PAE 11.81PAE 11.82PAE Bacteria cause milk to go sour by generating lactic acid. Devise an experiment that could measure the activation energy for the production of lactic acid by bacteria in milk. Describe how your experiment will provide the information you need to determine this value. What assumptions must be made about this reaction?11.84PAE 11.85PAE 11.86PAE 11.87PAE 11.88PAE 11.89PAE 11.90 Draw a hypothetical activation energy diagram for an uncatalyzed reaction. On the same set of coordinates, draw a similar graph for the catalyzed reaction. Why does reaction rate increase with the use of the catalyst?11.91PAE 11.92PAE 11.93 On a particular day, the ozone level in Milwaukee exceeded the EPAs 1-hour standard of 0.12 ppin by 10 ppb. How many ozone molecules would be present in 1 liter of air at the detection site?11.94PAE The following is a thought experiment. Imagine that you put a little water in a test tube and add some NaF crystals. Immediately after you add NaF, you observe that the crystals begin dissolving. The quantity of solid NaF decreases, hut before long, it appears that no more NaF is dissolving. The solution is saturated. The equation for the dissolution of NaF in water is NaF(s) —* Na (aq) + F~(aq). As NaF dissolves, what do you think happens to the rate of dissolution? Describe w hat is occurring on the molecular level. Assume that the reverse reaction, Na+(aq) + F“(aq) —* NaF(s), also occurs as the crystal dissolves. In other words, both dissolution and precipitation are taking place. When it appears that there is no more change in the quantin’ of NaF dissolving (the solution is saturated), w hat has happened to the rates of the forward and reverse reactions? Explain your answer.The following statements relate to the reaction for the formation of HI: H2(g) + I2(g) -* 2 HI(g) Rate = it[HJ [I2J Determine which of the following statements are true. If a statement is false, indicate why it is incorrect. The reaction must occur in a single step. This is a second-order reaction overall. Raising the temperature will cause the value of k to decrease. Raising the temperature lowers the activation energy' for this reaction. If the concentrations of both reactants are doubled, the rate will double. Adding a catalyst in the reaction will cause the initial rate to increase.11.97PAE Experiments show that the reaction of nitrogen dioxide with fluorine, 2 NO2(g) + F2(g) —* 2 FNO2(g) has the rate law Rate = *[NO2][FJ The reaction is thought to occur in two steps. Step 1: NO2(g) + F,(g) —* FNO,(g) + F(g) Step 2: NO2(g) + F(g) — FNO2(g) Show that the sum of this sequence of reactions gives the balanced equation for the overall reaction. Which step is rate determining?Substances that poison a catalyst pose a major concern for many engineering designs, including those for catalytic converters. One design option is to add materials that react with potential poisons before they reach the catalyst. Among the commonly encountered catalyst poisons are silicon and phosphorus, which typically form phosphate or silicate ions in the oxidizing environment of an engine. Group 2 elements are added to the catalyst to react with these contaminants before they reach the working portion of the catalytic converter. If estimates show that a catalytic converter will be exposed to 625 g of silicon during its lifetime, what mass of beryllium would need to be included in the design?11.100PAE 11.101PAE 11.102 Suppose that you are studying a reaction and need to determine its rate law. Explain what you would need to measure in order to accomplish this in a single experiment, and how you could use graphical methods to get from the experimental data to a complete rate law.11.103PAE 11.104PAE 11.105PAE 11.106PAE 11.1047 Fluorine often reacts explosively. What does this fact suggest about fluorine reactions at the molecular level?11.108PAE 11.109PAE When formic acid is heated, it decomposes to hydrogen and carbon dioxide in a first-order decay: HCOOH(g)CO2(g)+H2(g) The rate of reaction is monitored by measuring the total pressure in the reaction container. Time (s) Pressure (torr) 0 220 50 324 100 379 150 408 200 423 250 431 300 435 Calculate the rate constant and half-life in seconds for the reaction. At the start of the reaction (time = 0), only formic acid is present. (HINT: Find the partial pressure of formic acid using Dalton's law of partial pressure and the reaction stoichiometry to find PHCOOH at each time.)list chemical reactions important in the production and weathering of concrete.Explain that equilibrium is dynamic, and that at equilibrium the forward and backward reaction rates are equal.3CO calculate equilibrium constants from experimental data.5CO calculate molar solubility from Kspor vice versa.7CO 8CO calculate the new equilibrium composition of a system after an applied stress.Explain the importance of both kinetic and equilibrium considerations in the design of industrial chemical process.Identify the first chemical step in the production of Portland cement. How is this reaction related to the chemistry that takes place in the carbonation of concrete?Explain why the hydration process for concrete is exothermic by considering the chemical bonds in the reactants and products.12.3PAE 12.4 In what geographical region of the country would a civil engineer be most likely to use concrete with air entraining admixtures in a design? Explain your answer.12.5PAE 12.6PAE 12.7PAE On your desk is a glass half-filled with water and a square glass plate to use as a cover for the glass. How would you set up a dynamic equilibrium using the glass, water, and glass plate? Once equilibrium is established in part (a), describe the processes that are occurring at the molecular level.An equilibrium involving the carbonate and bicarbonate ions exists in natural waters: HCO5_(aq) «=* H+(aq) + COf-(aq) Assuming that the reactions in both directions are elementary' processes: Write rate expressions for the forward and reverse reactions. Write an expression for the equilibrium constant based on the rates of the forward and reverse reactions.A small quantity of a soluble salt is placed in water. Equilibrium between dissolved and undissolved salt may or may not be attained. Explain.12.11PAE 12.12PAE Write equilibrium (mass action) expressions for each of the following reactions. 2 NOBr(g) 2 NO(g) + Br,(g) 4 HCl(g) + O,(g)2 H20(g) + 2 Cl,(g) SO2(g) + yO2(g)«=sSO3(g) CH»(g) +‘2 O2(g) CO2(g) + 2 H2O(g) C2H,-OH(g) + 3 O2(g) «=* 2 CO2(g) + 3 H2O(g)What is the difference between homogeneous equilibrium and heterogeneous equilibrium?Write equilibrium expressions for each of the following heterogeneous equilibria. CaCO,(s) ** Ca2+(aq) + COf "(aq) AgCl(s) «=* Ag+(aq) + Cl_(aq) Mg5(PO4)2(s) «=* 3 Mg2+(aq) + 2 PO4J’(aq) Zn(s) + Cu*+(aq) «=* Cu(s) + Zn2+(aq)Write equilibrium expressions for each of the following equilibria. 2 C(s) + O2(g) «=* 2 CO(g) Zn (aq) + H2S(g) *=* ZnS(s) + 2 H (aq) HCl(g) + H2O(€) 5=i H,O+(aq) + Cl"(aq) (d) H2(g) + | O2(g) s=s H2O(g)12.17 Which of the following is more likely to precipitate sulfate ions? PbSO4(s) Pb*+(aq) + SO42’(aq) K = 1.8 X IO"8 CaSO4(s) i=i Ca2+(aq) + SO42'(aq) K = 9.1 X 10-6 The reaction, 3 H2(g) + N2(g) (g), has the fol lowing equilibrium constants at the temperatures given: atT=25°C,K= 2.8 X 104 at T = 500°C, A = 2.4 X IO"7 At which temperature are reactants favored? At which temperature are products favored? YVhat can you say about the reaction if the equilibrium constant is 1.2 at 127°C?12.19 For each of the following equations, write the equilibrium expression for the reverse reaction. 2C(s) + O,(g)^2CO(g) AgCl(s)5=BAg+(aq) + Cr Consider the following equilibria involving SO2(g) and their corresponding equilibrium constants. SO2(g) + |o2(g)^SO}(g) A, £ 2 SO,(g) «=* 2 SO,(g) + O,(g) A, Which of the following expressions relates A, to A2? A2 = A,2 A,2 = A, A2 = A, A2 = 1/A, A2 = 1/A,2 12.21PAE 12.22PAE 12.23PAE 12.24PAE 12.25PAE The following data were collected for the reaction, H2(g) + L(g) ** - HI(g), at equilibrium at 25°C: [HJ = 0.10 mol L-1, [IJ = 0.20 mol L"\ [HI] = 4.0 mol L’1 Calculate the equilibrium constant for the reaction at this temperature.The following data were collected for a system at equilibrium at 140°C. Calculate the equilibrium constant for the reaction, 3 H2(g) + N2(g) 5=^ 2 NHt(g) at this temperature. [H2] = 0.10 mol L_1, [NJ = 1.1 mol L"1, [NHJ = 3.6 X 10"-mol L'1 12.28PAE Nitrosyl chloride, NOCI, decomposes to NO and Cl, at high temperatures: 2NOCl(g)^2NO(g) + Cl,(g) Suppose you place 2.00 mol NOCI in a 1.00-L flask and raise the temperature to 462°C. When equilibrium has been established, 0.66 mol NO is present. Calculate the equilibrium constant Kcfor the decomposition reaction from these data.Hydrogen gas and iodine gas react via the following equation: H2(g) + I2(g)2 HI(g) \ = 76 (at 600 K) If 0.050 mol HI is placed in an empty 1.0-L flask at 600 K, what are the equilibrium concentrations of HI,I2, and Ht?12.31 A system consisting of 0.100 mole of oxygen gas, O2, is placed in a closed 1.00-L container and is brought to equilibrium at 600 K: O2(g)«=*2O(g)K=2.8x IO’59 What are the equilibrium concentrations of O and O2?12.32PAE 12.33PAE 1’he reaction in Exercise 12.33 was repeated. This time, the reaction began when only NO was injected into the reaction container. 110.200 mol L_l NO was injected, what were the equilibrium concentrations of all species? The following reaction establishes equilibrium at 2000 K: N2(g) + O2(g) ^2 NO K = 4.1 X 10~4 If the reaction began with 0.100 mol L-1 of N2 and 0.100 mol L"' ofO2, what were the equilibrium concentrations of all species?In the reaction in Exercise 12.33, another trial was carried out. The reaction began with an initial concentration of N2 equal to the initial concentration of NO. Each had a concentration of 0.100 mol L-1. WTat were the equilibrium concentrations of all species? The following reaction establishes equilibrium at 2000 K: N2(g) + O2(g) ^2 NO K = 4.1 X 10~4 If the reaction began with 0.100 mol L-1 of N2 and 0.100 mol L'1 ofO2, what were the equilibrium concentrations of all species?The experiment in Exercise 12.33 was redesigned so that the reaction started with 0.15 mol each of N2 and O2 being injected into a 1.0-L container at 2500 K. The equilibrium constant at 2500 K is 3.6 X 10“’. What was the composition of the reaction mixture after equilibrium was attained? The following reaction establishes equilibrium at 2000 K: N2(g) + O2(g) *2 2 NO K = 4.1 X IO-4 If the reaction began with 0.100 mol L-1 of N2 and 0.100 mol L-’ ofO2, what were the equilibrium concentrations of all species?Again the experiment in Exercise 12.33 was redesigned. This time, 0.15 mol each of N, and O2 was injected into a 5.0-L container at 2500 K, at which the equilibrium constant is 3.6 X 10-?. What was the composition of the reaction mixture at equilibrium? l'he following reaction establishes equilibrium at 2000 K: N2(g) + O2(g) *2 2 NO K = 4.1 X IO-4 If the reaction began with 0.100 mol L-1 of N2 and 0.100 mol L-’ ofO2, what were the equilibrium concentrations of all species?At a particular temperature, the equilibrium constant, A, for the dissociation of N,O4 into NO, is 133. If the initial concentration of N,O4 is 0.100 mol L-1, what are the concentrations of both species at equilibrium? N2O4 2 NO,A student is simulating the carbonic acid—hydrogen carbonate equilibrium in a lake: H2CO5(aq)«=* H+(aq) 4 HCO,'(aq) K = 4.4 X IO-7 She starts with 0.1000 M carbonic acid. W hat are the concentrations of all species at equilibrium?Because carbonic acid undergoes a second ionization, the student in Exercise 12.39 is concerned that the hydrogen ion concentration she calculated is not correct. She looks up the equilibrium constant for the reaction HCO,-(aq) «=* H+(aq) + COf'(aq) Upon finding that the equilibrium constant for this reaction is 4.8 X 10“H, she decides that her answer in Exercise 12.39 is correct. Explain her reasoning. A student is simulating the carbonic acid—hydrogen carbonate equilibrium in a lake: H,CO,(aq) 5=6 H+(aq) + HCO,'(aq) K = 4.4 X 10'7She starts with 0.1000 A1 carbonic acid. W hat are the concentrations of all species at equilibrium?Because calcium carbonate is a sink for CO32- in a lake, the student in Exercise 12.39 decides to go a step further and examine the equilibrium between carbonate ion and CaCOj. The reaction is Ca2+(aq) + COj2_(aq) ** CaCO,(s) The equilibrium constant for this reaction is 2.1 X 10*. If the initial calcium ion concentration is 0.02 AI and the carbonate concentration is 0.03 AI, what are the equilibrium concentrations of the ions? A student is simulating the carbonic acid—hydrogen carbonate equilibrium in a lake: H2COj(aq) H+(aq) + HCO}‘(aq) K = 4.4 X 10"7 She starts with 0.1000 AI carbonic acid. What are the concentrations of all species at equilibrium?12.42 The following reaction is in equilibrium in lake water: HCO,_(aq) + H+(aq)«=*H,CO,(aq) Predict the change in the reaction quotient, Q, for each disturbance below and use that prediction to explain how the equilibrium is shifted by the stress. NaHCOj is added to the lake. H,CO}is added. NaOH is added.12.43PAE 12.44PAE The following equilibrium is established in a closed container: C(s)+O2(g)CO2(g)H=393kJmol1 How does the equilibrium shift in response to each of the following stresses? (a) The quantity of solid carbon is increased. (b) A small quantity of water is added, and CO2 dissolves in it. (c) The system is cooled. (d) The volume of the container is increased.Write the K_, expression for each of the following equilih ria for dissolution of the salt in water. Agl(s) *=* Ag+(aq) + I"(aq) Phl,(s)«=± Pb’+(aq) + 2 r(aq) Hg?L «=* Hg<+(aq) + 2 I_(aq) Cu(IO,)2 *=* Ctr+(aq) + 2 IO,-(aq)12.47PAE calculate the molar solubility of the following compounds. (a) MgF2, (b) Fe(OH)3, (c) Mg3(PO4)2 12.49 The Safe Drinking Water Act of 1974 established the maximum permitted concentration of silver ion at 0.05 ppm. What is the concentration of Ag+ in parts per million in a saturated solution of AgCl? (NOTE: 1 ppm = 1 mg of solute/L of solution.)In Exercise 12.49, what is the allowed concentration of AgCl in g per 100 g of water? The Safe Drinking Water Act of 1974 established the maximum permitted concentration of silver ion at 0.05 ppm. What is the concentration of Ag+ in parts per million in a saturated solution of AgCl? (NOTE: 1 ppm = 1 mgofsolute/L of solution.)12.51PAE Because barium sulfate is opaque to X-rays, it is suspended in water and taken internally to make the gastrointestinal tract visible in an X-ray photograph. Although barium ion is quite toxic, barium sulfate’s /Csp of 1.1 X 10-,<) gives it such low solubility' that it can be safely consumed. What is the molar solubility' of BaSO4. What is its solubility' in grams per 100 g of water?The ore cinnabar (HgS) is an important source of mercury. Cinnabar is a red solid whose solubility in water is 5.5 X 10-2 mol L-1. Calculate its \p. What is its solubility' in grams per 100 g of water?12.54PAE From the solubility data given for the following com pounds, calculate their solubility product constants. CuBr, copper(I) bromide, 1.0 X 10“ ’ g/L Agl, silver iodide, 2.8 X 10-' g/10 mL Pb}(PO4)2, lead(II) phosphate, 62 X 10" g/L Ag2SO4, silver sulfate, 5.0 mg/mL The solubility of magnesium fluoride, MgF2, in water is 0.016 g/L. What is the solubility, in grams per liter, of magnesium fluoride in 0.020 M sodium fluoride, NaF?Solid Na2SO4 is added slowly to a solution that is 0.10 M in PbfNO,), and 0.10 M in Ba(NO})2. In what order will solid PbSO4 and BaS04 form? Calculate the percentage of B.r * that precipitates just before PbSO4 begins to precipitate.Will a precipitate of Mg(OH)2 form when 25.0 mL of 0.010 M NaOH is combined with 75.0 mL of a 0.10 M solution of magnesium chloride?Use the web to look up boiler scale and explain chemically why it is a problem in equipment where water is heated (such as in boilers).12.60PAE 12.61PAE 12.62 Write the formula of the conjugate acid of each of the following bases, (a) OH-, (b) NHj, (c) CHjNHt, (d) HPO/-, (e) CO.,2’12.63 For each of the following reactions, indicate the Bronsted-Lowrv acids and bases. What are the conjugate acid-base pairs? CN’(aq) + H2O(€) «=* HCN(aq) + OH’(aq) HCO}-(aq) + H,o+(aq) +* H2CO,(aq) + H,O(€) (C) CH,CtX)H(aq) + HS~(aq)i=i CH}COO"(aq) + H2S(aq)What are the products of each of the following acid-base reactions? Indicate the acid and its conjugate base and the base and its conjugate acid. HC1O4+ H2O — NH/ + H2O -» HCOr + OH" —12.65PAE 12.66PAE 12.67 Hydrofluoric acid is a weak acid used in the building industry to etch patterns into glass for elegant windows. Because it dissolves glass, it is the only inorganic acid that must be stored in plastic containers. A 0.1 M solution of HF has a pH of 2.1. Calculate [Hj0"| in this solution.The pH of a 0.129 M solution of a weak acid, HB, is 2.34. What is Kafor the weak acid?Calculate the pH of a 0.10 M solution of propanoic acid and determine its percent ionization.Find the pH of a 0.115 M solution of NH3(aq).Acrylic acid is used in the polymer industry in the production of acrylates. Its K, is 5.6 X 10“’. What is the pH of a 0.11 M solution of acrylic acid, CH2CHCOOH?12.72PAE 12.73PAE 12.74PAE Cyanic acid (HOCN) is a weak acid with AL, = 3.5 X IO-4. Consider the titration of 25.0 inL of 0.125 M HOCN with 0.125 M NaOH. Calculate the pH of the solution at each of the following points. Before any NaOH has been added. .After 12.5 mL of NaOH has been added. After 23.0 inL of NaOH has been added. .After 27.0 mL of KOH have been added. Use your calculator or a spreadsheet to plot the titration curve, and use your graph to estimate the pH at the equivalence point.In a particular experiment, the equilibrium constant measured for the reaction, Cl2(g)+NO2(g)Cl2NO2(g), is 2.8. Based on this measurement, calculate AG° for this reaction. Calculate AG° using data from Appendix E at the back of the book and discuss the agreement between your two calculations.12.77PAE 12.78PAE 12.79PAE 12.80PAE 12.81PAE 12.82PAE 12.83PAE 12.84PAE 12.85 In the figure, orange fish are placed in one aquarium and green fish in an adjoining aquarium. The two tanks are separated by a removable partition that is initially closed. Describe what happens in the first few minutes after the partition is opened. WTiat would you expect to see several hours later? How is this system analogous to dynamic chemical equilibrium?For the system in the preceding problem, show the equilibrium condition in terms of the rates of the forward and reverse reactions.12.87PAE Which of the following is more likely to precipitate the hydroxide ion? Cu(OH)2(s) *=» Ctr+(aq) + 2 OH’(aq) K = 1.6 X IO-19 Ca(OH)2(s) *=» Ca2+(aq) + 2 OH’(aq) K = 7.9 X 10"6 12.89PAE 12.90PAE In the following equilibrium in a closed system, indicate how the equilibrium is shifted by the indicated stress: HF(g)+H2O(l)H3O+(aq)+F(aq) (a) Additional HF(g) is added to the system. (b) Water is added. (c) Ca( NO3)2 solution is added, and CaF2 precipitates. (d) The volume is reduced. (e) KOH is added. (f) A catalyst is added.Consider the following system: 4NH3(g)+3O2(g)2N2(g)+6H2O(l)H=153.04kJ (a) How will the amount of ammonia at equilibrium be affected by (1) removing O2(g) ? (2) adding N2(g)? (3) adding water N2(g) ? (4) expanding the container at constant pressure? (5) increasing the temperature? (b) Which of the above factors will increase the value of K? Which will decrease it?The decomposition of NH4HS , NH4HS(s)NH3(g)+H2S(g) is an endothermic process. Using Le principle, explain how increasing the temperature would affect the equilibrium. If more NH4HS is added to a flask in which this equilibrium exists, how is the equilibrium affected? What if some additional NH3 is placed in the flask? What will happen to the pressure of NH3 if some H2S is removed from the flask?You are designing a process to remove carbonate ions from an aqueous system by precipitation. If the effectiveness of the process is the only concern (meaning there are no environmental or other issues involved), which of the following metal ions would be the best choice: Ca2+,Fe2+,Pb2+,orAg2+ ? Explain your answer. Salt Ksp CaCO3 4.8109 FeCO3 3.51011 PbCO3 1.51013 Ag2CO3 8.21012 Equal amounts of two gases, A and B3, are placed in an evacuated container and react to form AB and B2. A(g)+B3(g)AB(g)+B2(g) The molecular scale diagram represents the relative amounts of each substance present once equilibrium is reached. Which of the following graphs best describes the progress of the reaction as it proceeds to equilibrium? Explain why the graph you chose must be the correct one.12.96PAE 12.97PAE 12.98PAE Solid CaCO3 ; is placed in a closed container and heated to 800 °C. What is the equilibrium concentration of Co2 in the following equilibrium, for which K=2.5103 ? CaCO3(s)CaO(s)+Co2(g)12.100 A reaction important in smog formation is O3(g)+NO(g)O2(g)+NO2(g)K=6.01034 (a) If the initial concentrations are [O3]=1.0106M,[NO]=1.0105M,[NO2]=2.5104M, and [O2]=8.2103M , is the system at equilibrium? If not, in which direction does the reaction proceed? (b) If the temperature is increased, as on a very warm day, will the concentrations of the products increase or decrease? (HINT: You may have to calculate the enthalpy change for the reaction to find out if it is exothermic or endothermic.)12.101 An engineer working on a design to extract petroleum from a deep thermal reservoir wishes to capture toxic hydrogen sulfide gases present by reaction with aqueous iron(II) nitrate to form solid iron(II) sulfide. (a) Write the chemical equation for this process, assuming that it reaches equilibrium. (b) What is the equilibrium constant expression for this system? (c) How can the process be manipulated so that it does not reach equilibrium, allowing the continuous removal of hydrogen sulfide?12.102 A chemical engineer is working to optimize the production of acrylonitrile to be used in the manufacture of carbon fibers. The reaction being used is the combination of propene gas, ammonia, and oxygen. The reaction is normally carried out at moderately high temperatures so all species are in the gas phase. (a) Write the equilibrium constant expression for this reaction. (b) The boiling point of acrylonitrile is 77 °C, and that of propene is -48 °C. What would the equilibrium expression be if this reaction were carried out at room temperature? (c) What characteristic of this reaction might cause the engineer to desire carrying out this reaction at room temperature?12.103 Methanol, CH3OH, can be produced by the reaction of CO with H2, with the liberation of heat. All species in the reaction are gaseous. What effect will each of the following have on the equilibrium concentration of CO? (a) Pressure is increased, (b) volume of the reaction container is decreased, (c) heat is added, (d) the concentration of CO is increased, (e) some methanol is removed from the container, and (f) H2 is added.12.104PAE 12.105 Using the kinetic-molecular theory, explain why an increase in pressure produces more N2O4 in the following system: N2O4(g)2NO2(g)12.106 The solubility of KCl is 34.7 g per 100 g of water at 20 °C. Calculate its molar solubility in (a) pure water and (b) 0.10 M NaCl.12.107PAE 12.108 A nuclear engineer is considering the effect of discharging waste heat from a power plant into a lake and estimates that this may warm the water locally to 25 °C. One question to be considered is the effect of this temperature change on the uptake of CO2 by the water. The equilibrium constant for the reaction CO2+H2OH2CO3 ; is K=1.7103 at 25 °C. Because bonds form, the reaction is exothermic. (a) Will this reaction progress further toward products at higher temperatures near the water discharge with its warmer water than it would in the cooler lake water? Explain your reasoning. (b) Carbonic acid has a Kaof 2.5104 at 25 °C. What is the equilibrium constant for the CO2+2H2OHCO3+H3O+? (c) What additional factor should the engineer be considering about CO2 gas, probably before considering this reaction chemistry?12.109 Copper(II) iodate has a solubility of 0.136 g per 100 g of water. Calculate its molar solubility in water and its Ksp.12.110 In Exercise 12.109, what do you predict would happen to an aqueous copper(ll) iodate equilibrium if sulfide ion, S2-, were added? The Kspof CuS is 8.71036 . 12.109 Copper(II) iodate has a solubility of 0.136 g per 100 g of water. Calculate its molar solubility in water and its Ksp.12.111 You have three white solids. What experiment could you carry out to rank them in order of increasing solubility?12.112PAE 12.113PAE 12.114PAE 12.115PAE 12.116PAE 12.117 The vapor pressure of water at 80.0 °C is 0.467 atm. Find the value of Kcfor the process H2O(l)H2O(g) at this temperature.12.118PAE 1CO 2CO • write and balance half-reactions for simple redox processes.4CO 5CO • use standard reduction potentials to predict the spontaneous direction of a redox reaction.• calculate the amount of metal plated, the amount of current needed, or the time required for an electrolysis process.8CO 9CO 10CO 13.1PAE 13.2PAE 13.3PAE 13.4PAE For the following oxidationreduction reactions, identify the half-reactions and label them as oxidation or reduction. (a) Cu(s)+Ni2+(aq)Ni(s)+Cu2+(aq) (b) 2Fe3+(aq)+3Ba(s)3Ba2+(aq)+2Fe(s)Which half-reaction takes place at the anode of an electrochemical cell? Which half-reaction takes place at the cathode?If a salt bridge contains KNO3 as its electrolyte, which ions diffuse into solution in the anode compartment of the galvanic cell? Explain your answer.If a salt bridge contains KNO3 as its electrolyte, which ions diffuse into solution in the cathode compartment of the galvanic cell? Explain your answer.The following oxidationreduction reactions are used in electrochemical cells. Write them using cell notation. (a) 2Ag+(aq)(0.50M)+Ni(s)2Ag(s)+Ni2+(aq)(0.20M) (b) Cu(s)+PtCl62-(aq)(0.10M)Cu2+(aq)(0.20M)+PtCl42-(aq)(0.10M)+2Cl(aq)(0.40M) (c) Pb(s)+SO42-(aq)(0.30M)+2AgCl(s)PbSO4(s)+2Ag(s)+2Cl(aq)(0.20M) (d) In a galvanic cell, one half-cell contains 0.010 M HCI and a platinum electrode, over which H2 is bubbled at a pressure of 1.0 atm. The other half-cell is composed of a zinc electrode in a 0.125 M solution of Zn(NO3)2.Write a balanced chemical equation for the overall reaction in each of the following galvanic cells. (a) Ag(s)|Ag+(aq)Sn4+(aq),Sn2+(aq)|Pt(s) (b) Al(s)|Al3+(aq)Cu2+(aq)|Cu(s) (c) Pt(s)|Fe2+(aq),Fe3+(aq)MnO4-(aq),Mn2+(aq)|Pt(s)For the reactions in parts (a) and (b) in the preceding problem, no anions at all are shown in the cell notation. Explain why this is not a concern.Explain why the terms cell potential and electromotive force mean the same thing in electrochemical cells.How does galvanic corrosion differ from uniform corrosion of iron?13.14PAE A student who has mercury amalgam fillings in some of her teeth is eating a piece of candy. She accidentally bites down on a piece of the aluminum foil wrapper and experiences a sharp sensation in her mouth. Explain what has happened in terms of electrochemistry.Based on the cell potential measured for the cells Co(s)|Co2+(aq) Cu 2+( aq)|Cu( s)E=0.614VFe(s)|Fe2+(aq) Cu 2+( aq)|Cu( s)E=0.777V what potential should you expect to find for the following cell? Fe(s)|Fe2+(aq)Co2+(aq)|Co(s)13.17PAE Four voltaic cells are set up. In each, one half-cell contains a standard hydrogen electrode. The second half-cell is one of the following: Cr3+(aq,1.0M)|Cr(s),Fe2+(aq,1.0M)|Fe(s),Cu2+(aq,1.0M)|Cu(s) , or Mg2+(aq,1.0M)|Mg(s) . (a) In which of the voltaic cells does the hydrogen electrode serve as the cathode? (b) Which voltaic cell produces the highest voltage? Which produces the lowest voltage?In tables of standard reduction potentials that start from large positive values at the top and proceed through 0.0 V to negative values at the bottom, the alkali metals are normally at the bottom of the table. Use your chemical understanding of alkali metals and how they behave in bonding to explain why this is so.In the table of standard reduction potentials, locate the half-reactions for the reductions of the following metal ions to the metal: Sn2+(aq), Au+(aq), Zn2+(aq), Co2+(aq), Ag+(aq), and Cu2+(aq). Among the metal ions and metals that make up these half-reactions: (a) Which metal ion is the weakest oxidizing agent? (b) Which metal ion is the strongest oxidizing agent? (c) Which metal is the strongest reducing agent? (d) Which metal is the weakest reducing agent? (e) Will Sn(s) reduce Cu2+(aq) to Cu(s)? (f) Will Ag(s) reduce Co2+(aq) to Co(s)? (g) Which metal ions on the list can be reduced by Sn(s)? (h) What metals can be oxidized by Ag+(aq)?Using values from the table of standard reduction potentials, calculate the cell potentials of the following cells. (a) Ga(s)|Ga3+(aq)Ag+(aq)|Ag(s) (b) Zn(s)|Zn2+(aq)Cr3+(aq)|Cr(s) (c) Fe(s),FeS(s)|S2-(aq)Sn2+(aq)|Sn(s)Using values from the table of standard reduction potentials, calculate the cell potentials of the following cells. (a) Fe(s)|Fe2+(aq)Hg2+(aq)|Hg(l) (b) Pt(s)|Fe2+(aq),Fe3+(aq)MnO4(aq),H+(aq),Mn2+(aq)|Pt(s) (c) Pt(s)|Cl2(g)|Cl-(aq)Au+(aq)|Au(s)One half-cell in a voltaic cell is constructed from a copper wire dipped into a 4.8103 M solution of Cu(NO3)2.The other half-cell consists of a zinc electrode in a 0.40 M solution of Zn(NO3)2. Calculate the cell potential at 298 K.Four metals, A, B, C, and D, exhibit the following properties. (i) Only A and C react with 1.0 M hydrochloric acid to give H2(g). (ii) When C is added to solutions of the ions of the other metals, metallic B, D, and A are formed. (iii) Metal D reduces Bn+ to give metallic B and Dn+. Based on this information, arrange the four metals in order of increasing ability to act as reducing agents.Use the Nernst equation to calculate the cell potentials of the following cells at 298 K. (a) 2Ag+(aq)(0.50M)+Ni(s)2Ag(s)+Ni2+(aq)(0.20M) (b Cu(s)+PtCl62(aq)(0.10M)Cu2+(aq)(0.20M)+PtCl42-(aq)(0.10M)+2Cl-(aq)(0.40M) (c) Pb(s)+SO42(aq)(0.30M)+2AgCl(s)PbSO4(s)+2Ag(s)+2Cl-(aq)(0.20M)One half-cell in a voltaic cell is constructed from a silver wire dipped into a AgNO3 solution of unknown concentration. The other half-cell consists of a zinc electrode in a 1.0 M solution of Zn(NO3)2. A potential of 1.48 V is measured for this cell. Use this information to calculate the concentration of Ag+(aq).We noted that a tin-plated steel can corrodes more quickly than an unplated steel can. In cases of galvanic corrosion, one cannot expect standard conditions. Suppose that you want to study the galvanic corrosion of tin-plated steel by constructing a cell with low concentrations of the ions. You have pieces of tin and iron. You also have a solution of tin(ll) chloride that is 0.05 M and one of iron(ll) nitrate that is 0.01 M. (a) Describe the half-reactions you construct for this experiment. (b) Which halfreaction will be the anode and which the cathode? (c) Based on the solutions you have, calculate the cell potential for your experiment.The following half-cells are available: Ag(s); Ag+(aq,1.0M)|Ag;Zn2+(aq,1.0M)|Zn(s);Cu2+(aq,1.0M)|Cu(s) ; and Co2+(aq,1.0M)|Co(s) . Linking any two half-cells makes a voltaic cell. Given four different half-cells, six voltaic cells are possible. These are labeled, for simplicity, Ag-Zn, Ag-Cu, Ag-Co, Zn-Cu, Zn-Co, and Cu-Co. (a) In which of the voltaic cells does the copper electrode serve as the cathode? In which of the voltaic cells does the cobalt electrode serve as the anode? (b) Which combination of half-cells generates the highest potential? Which combination generates the lowest potential?13.29PAE 13.30PAE In May 2000, a concrete pedestrian walkway collapsed in North Carolina, injuring more than 100 people. Investigation revealed that CaCl2 had been mixed into the grout that filled the holes around the steel reinforcing cables inside the concrete, resulting in corrosion of the cables, thus weakening the structure. Based on your understanding of corrosion, explain why the use of chloride compounds in steel-reinforced concrete is discouraged by the concrete industry.13.32PAE Calculate the standard free energy change for the following reactions using the standard cell potentials for the half-reactions that are involved. (a) Fe(s)+Hg22+(aq)Fe2+(aq)+2Hg(l) (b Fe3+(aq)+Ag(s)+Cl-(aq)Fe2+(aq)+AgCl(s) (c) 2MnO4(aq)+5Zn(s)+16H3O+(aq)2Mn2+(aq)+5Zn2+(aq)+24H2O(l)Suppose that you cannot find a table of standard reduction potentials. You remember that the standard reduction potential of Cu2++2eCu(s) is 0.337 V. Given that Gf(Cu2+)=65.49kJmol-1 and that Gf(Ni2+)=45.6kJmol-1 , determine the standard reduction potential of Ni|Ni2+ from these data.13.35PAE Which of the following reactions is (are) spontaneous at standard conditions? (a) Zn(s)+2Fe3+(aq)Zn2+(aq)+2Fe2+(aq) (b) Cu(s)+2H+(aq)Cu2+(aq)+H2(g) (c) 2Br(aq)+I2(s)Br2(l)+2I(aq)Consult a table of standard reduction potentials and determine which of the following reactions are spontaneous under standard electrochemical conditions. (a) Mn(s)+2H+(aq)H2(g)+Mn2+(aq) (b) 2Al3+(aq)+3H2(g)2Al(s)+6H+(aq) (c) 2Cr(OH)3(s)+6F(aq)2Cr(s)+6OH(aq)+3F2(g) (d) Cl2(g)+2Br(aq)+Br2(l)+2Cl(aq)The equilibrium constant for a reaction is 31015 (a) Without carrying out any calculation, discuss whether ?G° for the reaction is positive or negative. (b) Calculate ?G° for this reaction.Some calculators cannot display results of an antilog calculation if the power of 10 is greater than 99. This shortcoming can come into play for determining equilibrium constants of redox reactions, which are sometimes quite large. Solve the following expressions for K: (a) logK=45.63 , (b) logK=25.00 , (c) logK=20.63 . is the relationship among the three expressions and the three answers? How can you use this relationship to solve problems that exceed 1099 even if your calculator will not carry out the calculation directly?Calculate the equilibrium constant for the following reactions using data from the standard reduction potential tables. (a) Cl2(g)+2Br-(aq)Br2(g)+2Cl-(aq) (b) Ni(s)+2Ag+(aq)2Ag(s)+Ni2+(aq) (c) I2(s)+Sn2+(aq)2I(aq)+Sn4+(aq)Use the standard reduction potentials for the reactions: AgCl(s)+eAg(s)+Cl-(aq) and Ag+(aq)+eAg(s) to calculate the value of Ksp for silver chloride at 298 K. How does your answer compare with the value listed in Table 12.4? Table 12.4 Ksp values Values for a few compounds illustrate the wide range over which solubility product constants can vary. Salt Ksp Ag2CO3 8.11012 Ag3PO4 1.31020 AgBr 5.31013 AgCl 1.81010 AgCN 6.01017 Ca3( PO4)2 2.01033 CaCO3 4.8109 FeCO3 3.51011 Mg3( PO4)2 9.91025 PbCO3 1.51013 PtS 9.91074 Zns 1.11021 Hydrogen peroxide is often stored in the refrigerator to help keep it from decomposing according to the reaction: Use information from the standard reduction potentials to determine the equilibrium constant of this reaction.Calculate the equilibrium constant for the redox reactions that could occur in the following situations and use that value to explain whether or not any reaction will be observed. (a) A piece of iron is placed in a 1.0 M solution of NiCl2(aq). (b) A copper wire is placed in a 1.0 M solution of Pb(NO3)2(aq).An engineer is assigned to design an electrochemical cell that will deliver a potential of exactly 1.52 V. Design and sketch a cell to provide this voltage, detailing the solutions, their concentrations, and the electrodes you will need. Write equations for all relevant reactions.A magnesium bar with a mass of 6.0 kg is attached to a buried iron pipe to serve as a sacrificial anode. An average current of 0.020 A flows between the bar and the pipe. (a) What reaction takes place at the surface of the magnesium bar? (b) What reaction takes place at the surface of the iron pipe? (C) In which direction do electrons flow between the two surfaces? (d) How many years would it take for the entire magnesium bar to be consumed?13.46PAE 13.47PAE 13.48PAE 13.49PAE If you put a 9-volt battery in a smoke detector in your home or apartment, you are not installing a single galvanic cell. Explain how and why this is so.If alkaline batteries were not alkaline but rather acidic (as in the older dry cell batteries), what extra difficulties could you envision with corrosion, based on reactions that are part of the table of standard reduction potentials?What would happen to the voltage of an alkaline battery if the zinc were replaced by steel? Assume that the zinc reaction is simply Zn|Zn2+ and that steel is iron.What product forms from the lead components of a lead storage battery? Why does mechanical shock (bumps) ultimately degrade the performance of the lead storage battery?13.54PAE 13.55PAE Assume the specifications of a Ni-Cd voltaic cell include delivery of 0.25 A of current for 1.00 h. What is the minimum mass of the cadmium that must be used to make the anode in this cell?13.57PAE What is the difference between active and passive electrolysis? Based on the common meanings of the words active and passive, what part of electrolysis is the focus of the name?13.59PAE 13.60PAE In an electroplating operation, the cell potential is sometimes 0 V. Why is a zero potential possible in electrolysis but not in a galvanic cell?

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